This invention relates to a snowmobile, and more particularly, to an improved drive and frame arrangement for a snowmobile.
Conventionally, snowmobiles have a frame assembly that supports, at the forward portion thereof, an internal combustion engine and a transmission that drives a drive belt positioned beneath the frame assembly and upon which the frame assembly is supported. A seat is carried by the frame assembly and generally overlies the drive belt. A pair of front skis are also carried by the frame assembly and are dirigibly supported for steering by a rider seated on the seat.
The drive belt generally is quite wide so as to improve stability and the transmission of power to the ground so as to propel the snowmobile. Of course, this means that the transmission for the drive belt must be disposed at a side of the drive belt and this driving transmission is driven from the engine in any of a variety of fashions. The rider, as is typical with this type of vehicle, is seated on the seat in straddle fashion and thus must have a place to position his legs. With the conventional types of drive constructions previously employed, the rider's legs must be splayed quite widely if they are to be disposed on opposite sides of the drive belt and the transmission that drives it. In order to avoid such uncomfortable seating positions, it has been the practice to move the seat rearwardly so that the rider's legs will be disposed behind the transmission driving the drive belt. This gives rise to not only a great length for the snowmobile, but also does not provide the desired balance or handling.
It is, therefore, a principal object of this invention to provide an improved snowmobile drive assembly that permits a more compact arrangement and affords comfortable seating.
It is a further object of this invention to provide a transmission assembly for a snowmobile that cab be positioned in a compact nature and permit the rider's feet to be placed outside of it without being unduly splayed.
It is a further object of this invention to provide an improved and compact drive assembly for a snowmobile.
Obviously, the frame assembly must support the engine and also accommodate the transmission. Conventionally, the frame assemblies include a pair of side members and the rider places his feet on footrests disposed outwardly of these side members. Because of the fact that the transmission assembly that drives the drive belt must be disposed at one side of the drive belt and outwardly therefor, it has heretofore been the practice to provide this transmission on the outside of the frame. This requires the rearward positioning of the rider and the other problems as aforenoted.
It is, therefore, a still further object of this invention to provide an improved frame assembly for a snowmobile that permits a compact assembly and permits a forwardly positioned rider.
It is a further object of this invention to provide an improved frame assembly for a snowmobile wherein the frame side members form, at least in part, the transmission case for the drive belt transmission.
As has been noted, the snowmobile typically employs a pair of front skis that are steered by a steering mechanism operated by the rider seated on the seat. This steering mechanism includes a steering column that is rotatably supported by the frame assembly and which generally is inclined upwardly and rearwardly from its forward connection to the steering skis. As a result of this disposition of the steering column, it has heretofore been the practice to position the engine either forwardly and/or above the steering column. This gives rise to added length to the snowmobile and also raises the center of gravity, which is not particularly desirable from a handling standpoint and from a stability standpoint.
It is, therefore, a still further object of this invention to provide an improved and compact steering arrangement for a snowmobile.
It is a further object of this invention to provide a steering arrangement for a snowmobile but permits the engine to be mounted low in the frame and thus maintain a low center of gravity.
The aforenoted types of steering constructions in which the steering column passes beneath and to the rear of the engine also causes the engine and a major portion of the transmission to be forwardly located. This tends to add to the weight on the front skis and reduce the amount of weight concentrated on the drive belt. As a result, traction can be decreased with this type of construction.
It is, therefore, a still further object of this invention to provide an improved engine and steering arrangement for a snowmobile that permits the engine to be located rearwardly and more over the drive belt than previous types of construction.
It has already been noted that the drive belt of a snowmobile is driven by a transmission from the engine. The drive belt transmission contains a drive belt drive shaft carrying a number of drive belt driving members that are engaged with the forward inner portion of the drive belt for driving it. This shaft obviously rotates about a transversely extending axis, and it has been the normal practice in snowmobiles to mount the engine so that its output shaft also rotates about a transversely extending axis. This means that with multiple cylinder engines that the exhaust manifold for the engine will also extend transversely. As a result, the exhaust system must reroute the exhaust gases from a transverse direction to a position wherein the exhaust gases can be discharged to the atmosphere and generally rearwardly of the engine. In other words, the exhaust system for the engine also extends the length of the engine assembly, either in a forward or rearward direction. This further compromises the location for the steering column.
It is, therefore, a still further object of this invention to provide an improved steering and engine arrangement for a snowmobile that permits a compact assembly.
It is a further object of this invention to provide an exhaust system and steering arrangement for a snowmobile wherein the steering column may pass between a portion of the exhaust system and the engine to occupy otherwise dead space and afford a compact arrangement.
Attendant to the transverse positioning of the engine in the snowmobile is also the requirement that the induction system extend either forwardly or rearwardly from the engine. This further complicates the layout of components of the snowmobile and can result in excess forward weight bias and added length for the snowmobile. As noted above, both of these features are relatively undesirable.
It is a still further object of this invention to provide an improved compact snowmobile arrangement that incorporates an induction system that can be interrelated to other components to afford a compact construction without unduly affecting the center of gravity.
It is a further object of this invention to provide an improved fuel tank and induction system layout for the driving power unit of a snowmobile.